U.S. patent number 8,730,697 [Application Number 13/472,762] was granted by the patent office on 2014-05-20 for method and apparatus for wireless power transmission using power receiver.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. The grantee listed for this patent is Jin Sung Choi, Young Tack Hong, Dong Zo Kim, Ki Young Kim, Nam Yun Kim, Sang Wook Kwon, Eun Seok Park, Yun Kwon Park, Young Ho Ryu, Chang Wook Yoon. Invention is credited to Jin Sung Choi, Young Tack Hong, Dong Zo Kim, Ki Young Kim, Nam Yun Kim, Sang Wook Kwon, Eun Seok Park, Yun Kwon Park, Young Ho Ryu, Chang Wook Yoon.
United States Patent |
8,730,697 |
Kim , et al. |
May 20, 2014 |
Method and apparatus for wireless power transmission using power
receiver
Abstract
A rectifier is provided. The rectifier includes a first
rectification unit having an anode connecting to a negative radio
frequency (RF) port and a cathode connecting to a positive direct
current (DC) port, a second rectification unit having an anode
connecting to a positive RF port and a cathode connecting to the
positive DC port, a third rectification unit having an anode
connecting to a ground and a cathode connecting to the negative RF
port, and a fourth rectification unit having an anode connecting to
the ground and a cathode connecting to the positive RF port. The
first rectification unit includes a plurality of first diodes that
are connected in parallel, and the second rectification unit
includes a plurality of second diodes that are connected in
parallel.
Inventors: |
Kim; Dong Zo (Yongin-si,
KR), Kwon; Sang Wook (Seongnam-si, KR),
Park; Yun Kwon (Dongducheon-si, KR), Park; Eun
Seok (Suwon-si, KR), Hong; Young Tack
(Seongnam-si, KR), Kim; Ki Young (Yongin-si,
KR), Ryu; Young Ho (Yongin-si, KR), Kim;
Nam Yun (Seoul, KR), Choi; Jin Sung (Gimpo-si,
KR), Yoon; Chang Wook (Yongin-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Kim; Dong Zo
Kwon; Sang Wook
Park; Yun Kwon
Park; Eun Seok
Hong; Young Tack
Kim; Ki Young
Ryu; Young Ho
Kim; Nam Yun
Choi; Jin Sung
Yoon; Chang Wook |
Yongin-si
Seongnam-si
Dongducheon-si
Suwon-si
Seongnam-si
Yongin-si
Yongin-si
Seoul
Gimpo-si
Yongin-si |
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A |
KR
KR
KR
KR
KR
KR
KR
KR
KR
KR |
|
|
Assignee: |
Samsung Electronics Co., Ltd.
(Suwon-si, KR)
|
Family
ID: |
47174805 |
Appl.
No.: |
13/472,762 |
Filed: |
May 16, 2012 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20120294054 A1 |
Nov 22, 2012 |
|
Foreign Application Priority Data
|
|
|
|
|
May 17, 2011 [KR] |
|
|
10-2011-0046188 |
|
Current U.S.
Class: |
363/84;
363/88 |
Current CPC
Class: |
H02M
7/08 (20130101); H02J 50/12 (20160201); H02J
7/025 (20130101); H02J 50/80 (20160201); H02J
50/70 (20160201); H02M 7/2195 (20210501); Y02B
70/10 (20130101) |
Current International
Class: |
H02M
7/68 (20060101) |
Field of
Search: |
;363/84,88,89 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2000-245077 |
|
Sep 2000 |
|
JP |
|
2008-295297 |
|
Dec 2008 |
|
JP |
|
10-2009-0011509 |
|
Feb 2009 |
|
KR |
|
10-2011-0009225 |
|
Jan 2011 |
|
KR |
|
WO 2009/140218 |
|
Nov 2009 |
|
WO |
|
Primary Examiner: Vu; Bao Q
Attorney, Agent or Firm: NSIP Law
Claims
What is claimed is:
1. A rectifier, comprising: a first rectification unit having an
anode and a cathode, the anode being connected to a negative radio
frequency (RF) port, and the cathode being connected to a positive
direct current (DC) port; a second rectification unit having an
anode and a cathode, the anode being connected to a positive RF
port, and the cathode being connected to the positive DC port; a
third rectification unit having an anode and a cathode, the anode
being connected to a ground, and the cathode being connected to the
negative RF port; and a fourth rectification unit having an anode
and a cathode, the anode being connected to the ground, and the
cathode being connected to the positive RF port, wherein the first
rectification unit comprises a plurality of first diodes that are
connected in parallel, and the second rectification unit comprises
a plurality of second diodes that are connected in parallel.
2. The rectifier of claim 1, wherein the first rectification unit
comprises two first diodes, and the second rectification unit
comprises two second diodes.
3. The rectifier of claim 1, wherein the third rectification unit
comprises a plurality of third diodes that are connected in
parallel, and the fourth rectification unit comprises a plurality
of fourth diodes that are connected in parallel.
4. The rectifier of claim 1, wherein the third rectification unit
comprises a first N-metal-oxide-semiconductor field-effect
transistor (N-MOSFET), wherein the fourth rectification unit
comprises a second N-MOSFET, wherein a gate of the first N-MOSFET
is connected to the positive RF port, a source of the first
N-MOSFET is connected to the negative RF port, and a drain of the
first N-MOSFET is connected to the ground, and wherein a gate of
the second N-MOSFET is connected to the negative RF port, a source
of the second N-MOSFET is connected to the ground, and a drain of
the second N-MOSFET is connected to the positive RF port.
5. The rectifier of claim 4, wherein a resistance of the first
N-MOSFET is equal to or less than 200 milliohm (m.OMEGA.), and an
input capacitance of the first N-MOSFET is equal to or less than
300 picofarads (pF), and wherein a resistance of the second
N-MOSFET is equal to or less than 200 m.OMEGA., and an input
capacitance of the second N-MOSFET is equal to or less than 300
pF.
6. The rectifier of claim 1, further comprising: a capacitor
connected to the positive DC port and the ground.
7. A power receiver, comprising: a resonator configured to receive
a power; a rectifier configured to receive the power from the
resonator via a positive radio frequency (RF) port and a negative
RF port, and to rectify the received power; and a direct current
(DC)-to-DC (DC/DC) converter configured to convert the rectified
power, wherein the rectifier comprises: a first rectification unit
having an anode and a cathode, the anode being connected to the
negative RF port, and the cathode being connected to a positive DC
port; a second rectification unit having an anode and a cathode,
the anode being connected to the positive RF port, and the cathode
being connected to the positive DC port; a third rectification unit
having an anode and a cathode, the anode being connected to a
ground, and the cathode being connected to the negative RF port;
and a fourth rectification unit having an anode and a cathode, the
anode being connected to the ground, and the cathode being
connected to the positive RF port, wherein the first rectification
unit comprises a plurality of first diodes connected in parallel,
and the second rectification unit comprises a plurality of second
diodes connected in parallel.
8. The power receiver of claim 7, wherein the third rectification
unit comprises a plurality of third diodes that are connected in
parallel, and the fourth rectification unit comprises a plurality
of fourth diodes that are connected in parallel.
9. The power receiver of claim 8, wherein the third rectification
unit comprises a first N-metal-oxide-semiconductor field-effect
transistor (N-MOSFET), wherein the fourth rectification unit
comprises a second N-MOSFET, wherein a gate of the first N-MOSFET
is connected to the positive RF port, a source of the first
N-MOSFET is connected to the negative RF port, and a drain of the
first N-MOSFET is connected to the ground, and wherein a gate of
the second N-MOSFET is connected to the negative RF port, a source
of the second N-MOSFET is connected to the ground, and a drain of
the second N-MOSFET is connected to the positive RF port.
10. The power receiver of claim 8, wherein the rectifier further
comprises a capacitor connected to the positive DC port and the
ground.
11. A power receiving method, comprising: receiving, by a
resonator, a power; receiving, by a rectifier, the power from the
resonator via a positive radio frequency (RF) port and a negative
RF port, and rectifying the received power; and converting, by a
direct current (DC)-to-DC (DC/DC) converter, the rectified power,
wherein the rectifier comprises: a first rectification unit having
an anode and a cathode, the anode being connected to the negative
RF port, and the cathode being connected to a positive DC port; a
second rectification unit having an anode and a cathode, the anode
being connected to the positive RF port, and the cathode being
connected to the positive DC port; a third rectification unit
having an anode and a cathode, the anode being connected to a
ground, and the cathode being connected to the negative RF port;
and a fourth rectification unit having an anode and a cathode, the
anode being connected to the ground, and the cathode being
connected to the positive RF port, wherein the first rectification
unit comprises a plurality of first diodes connected in parallel,
and the second rectification unit comprises a plurality of second
diodes connected in parallel.
12. The power receiving method of claim 11, wherein the third
rectification unit comprises a plurality of third diodes that are
connected in parallel, and the fourth rectification unit comprises
a plurality of fourth diodes that are connected in parallel.
13. The power receiving method of claim 11, wherein the third
rectification unit comprises a first N-metal-oxide-semiconductor
field-effect transistor (N-MOSFET), wherein the fourth
rectification unit comprises a second N-MOSFET, wherein a gate of
the first N-MOSFET is connected to the positive RF port, a source
of the first N-MOSFET is connected to the negative RF port, and a
drain of the first N-MOSFET is connected to the ground, and wherein
a gate of the second N-MOSFET is connected to the negative RF port,
a source of the second N-MOSFET is connected to the ground, and a
drain of the second N-MOSFET is connected to the positive RF
port.
14. The power receiving method of claim 11, wherein the rectifier
further comprises a capacitor connected to the positive DC port and
the ground.
15. A non-transitory computer readable recording medium storing a
program to cause a computer to implement the method of claim 11.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application claims the benefit under 35 U.S.C. .sctn.119(a) of
Korean Patent Application No. 10-2011-0046188, filed on May 17,
2011, in the Korean Intellectual Property Office, the entire
disclosure of which is incorporated herein by reference for all
purposes.
BACKGROUND
1. Field
The following description relates to a method and an apparatus for
wireless power transmission using a power receiver.
2. Description of Related Art
A wireless power refers to energy transferred from a wireless power
transmitter to a wireless power receiver via magnetic coupling.
Research has been conducted on various products ranging from a high
power application requiring a power above 100 W to a low power
application requiring a power less than 10 W. As an example, a
wireless power application requiring a power of less than 10 W may
relate to a mobile device.
A wireless power receiver may charge a battery using a received
energy. A wireless power transmission and charging system includes
a source device and a target device. The source device may
wirelessly transmit power. On the other hand, the target device may
wirelessly receive power. In other words, the source device may be
referred to as a wireless power transmitter, and the target device
may be referred to as a wireless power receiver.
The source device includes a source resonator, and the target
device includes a target resonator. As an aspect, magnetic coupling
or resonance coupling may be formed between the source resonator
and the target resonator. The source device and the target device
may communicate with each other. During communications, the
transmission or reception of control and state information may
occur.
SUMMARY
In one general aspect, a rectifier is provided. The rectifier
includes a first rectification unit having an anode and a cathode,
the anode being connected to a negative radio frequency (RF) port,
and the cathode being connected to a positive direct current (DC)
port, a second rectification unit having an anode and a cathode,
the anode being connected to a positive RF port, and the cathode
being connected to the positive DC port, a third rectification unit
having an anode and a cathode, the anode being connected to a
ground, and the cathode being connected to the negative RF port,
and a fourth rectification unit having an anode and a cathode, the
anode being connected to the ground, and the cathode being
connected to the positive RF port. The first rectification unit
includes a plurality of first diodes that are connected in
parallel, and the second rectification unit includes a plurality of
second diodes that are connected in parallel.
The first rectification unit may include two first diodes, and the
second rectification unit may include two second diodes.
The third rectification unit may include a plurality of third
diodes that are connected in parallel, and the fourth rectification
unit may include a plurality of fourth diodes that are connected in
parallel.
The third rectification unit may include a first
N-metal-oxide-semiconductor field-effect transistor (N-MOSFET). The
fourth rectification unit may include a second N-MOSFET. A gate of
the first N-MOSFET may be connected to the positive RF port, a
source of the first N-MOSFET may be connected to the negative RF
port, and a drain of the first N-MOSFET may be connected to the
ground. A gate of the second N-MOSFET may be connected to the
negative RF port, a source of the second N-MOSFET may be connected
to the ground, and a drain of the second N-MOSFET may be connected
to the positive RF port.
A resistance of the first N-MOSFET may be equal to or less than 200
milliohm (m.OMEGA.), and an input capacitance of the first N-MOSFET
may be equal to or less than 300 picofarads (pF). A resistance of
the second N-MOSFET may be equal to or less than 200 m.OMEGA., and
an input capacitance of the second N-MOSFET may be equal to or less
than 300 pF.
The rectifier may include a capacitor connected to the positive DC
port and the ground.
In another aspect, a power receiver is provided. The power receiver
includes a resonator configured to receive a power, a rectifier
configured to receive the power from the resonator via a positive
radio frequency (RF) port and a negative RF port, and to rectify
the received power, and a direct current (DC)-to-DC (DC/DC)
converter configured to convert the rectified power. The rectifier
includes a first rectification unit having an anode and a cathode,
the anode being connected to the negative RF port, and the cathode
being connected to a positive DC port, a second rectification unit
having an anode and a cathode, the anode being connected to the
positive RF port, and the cathode being connected to the positive
DC port, a third rectification unit having an anode and a cathode,
the anode being connected to a ground, and the cathode being
connected to the negative RF port, and a fourth rectification unit
having an anode and a cathode, the anode being connected to the
ground, and the cathode being connected to the positive RF port.
The first rectification unit includes a plurality of first diodes
connected in parallel, and the second rectification unit includes a
plurality of second diodes connected in parallel.
The third rectification unit may include a plurality of third
diodes that are connected in parallel, and the fourth rectification
unit may include a plurality of fourth diodes that are connected in
parallel.
The third rectification unit may include a first
N-metal-oxide-semiconductor field-effect transistor (N-MOSFET). The
fourth rectification unit may include a second N-MOSFET. A gate of
the first N-MOSFET may be connected to the positive RF port, a
source of the first N-MOSFET may be connected to the negative RF
port, and a drain of the first N-MOSFET may be connected to the
ground. A gate of the second N-MOSFET may be connected to the
negative RF port, a source of the second N-MOSFET may be connected
to the ground, and a drain of the second N-MOSFET may be connected
to the positive RF port.
The rectifier may include a capacitor connected to the positive DC
port and the ground.
In another aspect, a power receiving method is provided. The power
receiving method includes receiving, by a resonator, a power,
receiving, by a rectifier, the power from the resonator via a
positive radio frequency (RF) port and a negative RF port, and
rectifying the received power, and converting, by a direct current
(DC)-to-DC (DC/DC) converter, the rectified power. The rectifier
includes a first rectification unit having an anode and a cathode,
the anode being connected to the negative RF port, and the cathode
being connected to a positive DC port, a second rectification unit
having an anode and a cathode, the anode being connected to the
positive RF port, and the cathode being connected to the positive
DC port, a third rectification unit having an anode and a cathode,
the anode being connected to a ground, and the cathode being
connected to the negative RF port, and a fourth rectification unit
having an anode and a cathode, the anode being connected to the
ground, and the cathode being connected to the positive RF port.
The first rectification unit includes a plurality of first diodes
connected in parallel, and the second rectification unit includes a
plurality of second diodes connected in parallel.
The third rectification unit may include a plurality of third
diodes that are connected in parallel, and the fourth rectification
unit may include a plurality of fourth diodes that are connected in
parallel.
The third rectification unit may include a first
N-metal-oxide-semiconductor field-effect transistor (N-MOSFET). The
fourth rectification unit may include a second N-MOSFET. A gate of
the first N-MOSFET may be connected to the positive RF port, a
source of the first N-MOSFET may be connected to the negative RF
port, and a drain of the first N-MOSFET may be connected to the
ground. A gate of the second N-MOSFET may be connected to the
negative RF port, a source of the second N-MOSFET may be connected
to the ground, and a drain of the second N-MOSFET may be connected
to the positive RF port.
The rectifier may include a capacitor connected to the positive DC
port and the ground.
A non-transitory computer readable recording medium storing a
program may cause a computer to implement the method.
Other features and aspects may be apparent from the following
detailed description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram illustrating an example of a wireless power
transmission system.
FIG. 2 is a diagram illustrating an example of a wireless power
transmitter.
FIG. 3 is a diagram illustrating another example of a wireless
power transmitter.
FIGS. 4 through 8 are diagrams illustrating examples of
resonators.
FIG. 9 is a diagram illustrating an example of an equivalent
circuit of a resonator of FIG. 3.
FIG. 10 is a diagram illustrating an example of a configuration of
a wireless power receiving and transmitting system.
FIG. 11 is a diagram illustrating an example of an equivalent model
of a Schottky diode.
FIGS. 12A and 12B are graphs illustrating examples of a
current-to-voltage characteristic of a Schottky diode.
FIG. 13 is a diagram illustrating an example of a full-bridge diode
rectifier circuit.
FIG. 14 is a diagram illustrating an example of a structure of a
dual diode full-bridge rectifier.
FIGS. 15A and 15B are graphs illustrating examples of
current-to-voltage curves indicating a voltage drop of the dual
diode full-bridge rectifier of FIG. 14.
FIGS. 16A and 16B are graphs illustrating examples of
current-to-voltage curves indicating a voltage drop of a
full-bridge rectifier in which three Schottky diodes are used in
parallel.
FIG. 17 is a diagram illustrating an example of a structure of a
dual diode cross-coupled transistor (TR) rectifier.
FIG. 18 is a graph illustrating a result of comparing an efficiency
of the dual diode full-bridge rectifier of FIG. 14 with an
efficiency of the dual diode cross-coupled TR rectifier of FIG.
17.
FIG. 19 is a flowchart illustrating an example of a power receiving
method.
Throughout the drawings and the detailed description, unless
otherwise described, the same drawing reference numerals will be
understood to refer to the same elements, features, and structures.
The relative size and depiction of these elements may be
exaggerated for clarity, illustration, and convenience.
DETAILED DESCRIPTION
The following detailed description is provided to assist the reader
in gaining a comprehensive understanding of the methods,
apparatuses, and/or systems described herein. Accordingly, various
changes, modifications, and equivalents of the systems, apparatuses
and/or methods described herein will be suggested to those of
ordinary skill in the art. Also, descriptions of well-known
functions and constructions may be omitted for increased clarity
and conciseness.
FIG. 1 illustrates an example of a wireless power transmission
system.
Referring to FIG. 1, the wireless power transmission system
includes a source device 110, and a target device 120.
The source device 110 may include an alternating current-to-direct
current (AC/DC) converter 111, a power detector 113, a power
converter 114, a control/communication unit 115, and a source
resonator 116.
The target device 120 may include a target resonator 121, a
rectification unit 122, a DC-to-DC (DC/DC) converter 123, a switch
unit 124, a charging unit 125, and a control/communication unit
126.
The AC/DC converter 111 may rectify an AC voltage in a band of tens
of hertz (Hz) output from a power supply 112 to generate a DC
voltage. The AC/DC converter 111 may output a DC voltage of a
predetermined level, or may adjust an output level of a DC voltage
based on the control of the control/communication unit 115.
The power detector 113 may detect an output current and an output
voltage of the AC/DC converter 111, and the power detector 113 may
transfer information on the detected current and the detected
voltage, to the control/communication unit 115. In addition, the
power detector 113 may detect an input current and an input voltage
of the power converter 114.
The power converter 114 may use a switching pulse signal in a band
of a few megahertz (MHz) to tens of MHz to convert a DC voltage of
a predetermined level to an AC voltage to generate a power.
As an example, the power converter 114 may use a resonance
frequency to convert a DC voltage to an AC voltage and the power
converter 114 may generate a "communication power used for
communication" or a "charging power used for charging." The
communication power and the charging power may be used in the
target device 120. The communication power may refer to an energy
used to activate a communication module and a processor of the
target device 120. Accordingly, the communication power may be
referred to as a "wake-up power." Additionally, the communication
power may be transmitted in the form of a constant wave (CW) for a
predetermined period of time. The charging power may refer to an
energy used to charge a battery connected to the target device 120
or a battery included in the target device 120. The charging power
may continue to be transmitted, at a higher power level than the
communication power, for a predetermined period of time. For
example, the communication power may have a power level of 0.1 Watt
(W) to 1 W, and the charging power may have a power level of 1 W to
20 W.
The control/communication unit 115 may control a frequency of a
switching pulse signal. The frequency of the switching pulse signal
may be determined under the control of the control/communication
unit 115. The control/communication unit 115 may control the power
converter 114 to generate a modulation signal to be transmitted to
the target device 120. In other words, the control/communication
unit 115 may use in-band communication to transmit various messages
to the target device 120. Additionally, the control/communication
unit 115 may detect a reflected wave, and the control/communication
unit 115 may demodulate a signal received from the target device
120 through an envelope of the detected reflected wave.
The control/communication unit 115 may use various schemes to
generate a modulation signal for in-band communication. The
control/communication unit 115 may turn on or off a switching pulse
signal, or may perform delta-sigma modulation, to generate a
modulation signal. Additionally, the control/communication unit 115
may generate a pulse-width modulation (PWM) signal with a
predetermined envelope.
The control/communication unit 115 may perform out-band
communication that employs a separate communication channel,
instead of a resonance frequency. The control/communication unit
115 may include a communication module. The communication module
may be a ZigBee module, a Bluetooth module, and the like. The
control/communication unit 115 may transmit data to the target
device 120 using the out-band communication or receive data from
the target device 120 using the out-band communication.
The source resonator 116 may transfer an electromagnetic energy to
the target resonator 121. As an aspect, the source resonator 116
may transfer a "communication power used for communication" to the
target device 120 or a "charging power used for charging" to the
target device 120 using a magnetic coupling with the target
resonator 121.
The target resonator 121 may receive the electromagnetic energy
from the source resonator 116. As an aspect, the target resonator
121 may receive the "communication power" or "charging power" from
the source device 110 using the magnetic coupling with the source
resonator 116. As another aspect, the target resonator 121 may use
the in-band communication to receive various messages from the
source device 110.
The rectification unit 122 may rectify an AC voltage to generate a
DC voltage. In this example, the AC voltage may be received from
the target resonator 121.
The DC/DC converter 123 may adjust a level of the DC voltage output
from the rectification unit 122, based on a capacity of the
charging unit 125. For example, the DC/DC converter 123 may adjust,
to, for example, 3 volt (V) to 10 V, the level of the DC voltage
output from the rectification unit 122.
The switch unit 124 may be turned on or off, under the control of
the control/communication unit 126. In response to the switch unit
124 being turned off, the control/communication unit 115 of the
source device 110 may detect a reflected wave. In other words, in
response to the switch unit 124 being turned off, the magnetic
coupling between the source resonator 116 and the target resonator
121 may be substantially reduced.
The charging unit 125 may include a battery. The charging unit 125
may use a DC voltage output from the DC/DC converter 123 to charge
the battery.
The control/communication unit 126 may use a resonance frequency to
perform in-band communication for transmitting or receiving data.
During the in-band communication, the control/communication unit
126 may detect a signal between the target resonator 121 and the
rectification unit 122, or detect an output signal of the
rectification unit 122 to demodulate a received signal. In other
words, the control/communication unit 126 may demodulate a message
received using the in-band communication.
As another aspect, the control/communication unit 126 may adjust an
impedance of the target resonator 121, to modulate a signal to be
transmitted to the source device 110. As an example, the
control/communication unit 126 may turn on or off the switch unit
124 to modulate the signal to be transmitted to the source device
110. For example, the control/communication unit 126 may increase
the impedance of the target resonator 121. Based on the increase of
the impedance of the target resonator 121, a reflected wave may be
detected from the control/communication unit 115 of the source
device 110. In this example, depending on whether the reflected
wave is detected, the control/communication unit 115 may detect a
binary number "0" or "1."
The control/communication unit 126 may also perform out-band
communication that employs a communication channel. The
control/communication unit 126 may include a communication module.
The communication module may be a ZigBee module, a Bluetooth
module, and the like. The control/communication unit 126 may
transmit to the source device 110 using the out-band communication
or receive data from the source device 110 using the out-band
communication.
FIG. 2 illustrates an example of a wireless power transmitter.
Referring to FIG. 2, the wireless power transmitter includes a
source resonator 210, a sub-resonator 220, and a magnetic field
distribution controller 230.
The source resonator 210 may form a magnetic coupling with a target
resonator. The source resonator 210 may wirelessly transmit power
to a target device through the magnetic coupling. The source
resonator 210 may have a loop shape as illustrated in FIG. 2. As
another aspect, the loop shape may be implemented in various
shapes. For example, the shapes may include a spiral shape, a
helical shape, and the like.
Additionally, the wireless power transmitter may include a matcher
(not illustrated) to be used in impedance matching. The matcher may
adjust a strength of a magnetic field of the source resonator 210
to an appropriate level. An impedance of the source resonator 210
may be determined by the matcher. The matcher may have the same
shape as the source resonator 210. Additionally, the matcher may
have a predetermined location relationship with a capacitor located
in the source resonator 210 to adjust the strength of the magnetic
field. For example, the matcher may be electrically connected to
the source resonator 210 in both ends of the capacitor.
As an example, the matcher may be located within a loop of the loop
structure of the source resonator 210. The matcher may change the
physical shape of the matcher to adjust the impedance of the source
resonator 210.
The sub-resonator 220 may be located within the source resonator
210. A plurality of sub-resonators may be located within the source
resonator 210. Additionally, a sub-sub-resonator may be located
within the sub-resonator 220. The sub-resonator 220 may influence a
distribution of a magnetic field formed within the source resonator
210. For example, a current flowing in the source resonator 210 may
form a magnetic field, and the formed magnetic field may induce a
current to the sub-resonator 220. In this example, a distribution
of the magnetic field formed within the source resonator 210 may be
determined based on a direction of the current flowing in the
source resonator 210 and in the sub-resonator 220. As another
aspect, the direction of the current flowing in the sub-resonator
220 may be determined based on a ratio of a resonance frequency of
the sub-resonator 220 to a resonance frequency of the source
resonator 210.
The resonance frequency of the source resonator 210 may be related
to an inductance value L, and a capacitance value C of the source
resonator 210. Similarly, the resonance frequency of the
sub-resonator 220 may be related to an inductance value and a
capacitance value of the sub-resonator 220.
The magnetic field distribution controller 230 may be located in a
predetermined area within the source resonator 210. The magnetic
field distribution controller 230 may control the direction of the
current flowing in the source resonator 210 or in the sub-resonator
220. The magnetic field distribution controller 230 may control the
distribution of the magnetic field formed within the source
resonator 210.
The direction of the current flowing in the source resonator 210,
or the direction of the current flowing in the sub-resonator 220
may be related to the ratio of the resonance frequency of the
sub-resonator 220 to the resonance frequency of the source
resonator 210.
The magnetic field distribution controller 230 may control the
resonance frequency of the source resonator 210, or the resonance
frequency of the sub-resonator 220. As an example, the magnetic
field distribution controller 230 may control the resonance
frequency of the source resonator 210 based on changing the
capacitance of the source resonator 210. As another aspect, the
magnetic field distribution controller 230 may control the
resonance frequency of the sub-resonator 220 based on adjusting the
capacitance and the inductance of the sub-resonator 220. The
magnetic field distribution controller 230 may adjust a length and
a width of a line that forms the sub-resonator 220 to control the
inductance value of the sub-resonator 220.
The magnetic field distribution controller 230 may control the
direction of the current flowing in the source resonator 210, or
the magnetic field distribution controller 230 may control the
direction of the current flowing in the sub-resonator 220, so that
the strength of the magnetic field formed within the source
resonator 210 may be increased or decreased.
As another aspect, the magnetic field distribution controller 230
may control the distribution of the magnetic field, so that the
magnetic field may be uniformly distributed in the source resonator
210. As an example, the magnetic field distribution controller 230
may control the resonance frequency of the sub-resonator 220, and
the magnetic field distribution controller 230 may control the
magnetic field to be uniformly distributed in the source resonator
210. The configuration of the sub-resonator 220 will be further
described with reference to FIG. 8.
The magnetic field distribution controller 230 may use a
sub-sub-resonator to control the distribution of the magnetic field
formed within the source resonator 210. The magnetic field
distribution controller 230 may control a resonance frequency of
the sub-sub-resonator, and the magnetic field distribution
controller 230 may compensate for the uniform distribution of the
magnetic field formed within the source resonator 210. The magnetic
field distribution controller 230 may control the direction of the
current flowing in the sub-resonator 220 and a direction of a
current flowing in the sub-sub-resonator, and the magnetic field
distribution controller 230 may control the distribution of the
magnetic field. The sub-sub-resonator may be located in the
sub-resonator 220. The sub-sub-resonator may support the
sub-resonator 220, and the sub-sub-resonator may compensate for the
distribution of the magnetic field formed within the source
resonator 210, so that the magnetic field may be uniformly
distributed. The sub-sub-resonator may compensate for the
distribution of the magnetic field adjusted by the sub-resonator
220, so that the magnetic field may be uniformly distributed in the
source resonator 210.
The magnetic field distribution controller 230 may include at least
one coil. The at least one coil may be used to induce the magnetic
field formed within the source resonator 210 towards the center of
the source resonator 210. As another aspect, the magnetic field
distribution controller 230 may use the at least one coil to
control the magnetic field formed within the source resonator 210
to be uniformly distributed.
The magnetic field distribution controller 230 may control a
resonance frequency of the at least one coil, so that a current may
flow in the at least one coil in the same direction as the current
flowing in the source resonator 210.
In an example, at least one coil may be located in the center of
the source resonator 210, and the at least one coil may form at
least one loop structure with different sizes. The magnetic field
distribution controller 230 may use the at least one coil of
various sizes to more precisely control the magnetic field formed
within the source resonator 210.
In another example, at least one coil having the same shape as
another coil may be located in a predetermined position within the
source resonator 210. The at least one coil having the same shape
as another coil may be located in various areas within the source
resonator 210. Under the control of the magnetic field distribution
controller 230, the at least one coil having the same shape as
another coil may increase or decrease the strength of the magnetic
field formed within the source resonator 210 in the various areas
in which the at least one coil having the same shape as another
coil is located.
In yet another example, the at least one coil may be located in the
center of the source resonator 210. The at least one coil may be
formed in a spiral shape. As another example, the at least one coil
may be formed with various shapes, and the at least one coil may
adjust the magnetic field formed within the source resonator
210.
The magnetic field distribution controller 230 may include a
plurality of shielding layers. The plurality of shielding layers
may have different sizes and heights located at the center of the
source resonator 210, and the plurality of shielding layers may
have a loop structure. Due to the plurality of shielding layers
being located at the center of the source resonator 210 and having
the loop structure, the magnetic field distribution controller 230
may induce the magnetic field formed within the source resonator
210 to be uniformly distributed. A magnetic flux of the magnetic
field formed within the source resonator 210 may be refracted from
the plurality of shielding layers, and the magnetic flux of the
magnetic field may be more concentrated on the center of the source
resonator 210.
The magnetic field distribution controller 230 may include a layer
formed of a mu negative (MNG) material, a double negative (DNG)
material, or a magneto-dielectric material. The magnetic field
distribution controller 230 may refract the magnetic flux of the
magnetic field formed within the source resonator 210, based on the
layer, and the magnetic field distribution controller 230 may
induce the magnetic field to be uniformly distributed in the source
resonator 210.
The magnetic field distribution controller 230 may adjust widths of
the shielding layers laminated in predetermined positions of the
source resonator 210 and the sub-resonator 220, and the magnetic
field distribution controller 230 may induce the magnetic field to
be uniformly distributed within the source resonator 210. Based on
the widths of the shielding layers, a refractive level of the
magnetic flux of the magnetic field formed within the source
resonator 210 may be changed. Accordingly, the magnetic field
distribution controller 230 may adjust the widths of the shielding
layers to control the magnetic field to be uniformly distributed
within the source resonator 210.
A target device may be located on the source resonator 210 of a pad
type. In this example, a gap between the source resonator 210 and
the target device may be less than a 2 or 3 centimeters (cm).
Accordingly, a parasitic capacitor may be formed between the source
resonator 210 and the target device. The parasitic capacitor may
influence the resonance frequency of the source resonator 210. The
magnetic field distribution controller 230 may adjust widths and
thicknesses of the shielding layers laminated in predetermined
positions of the source resonator 210 and the sub-resonator 220,
and the magnetic field distribution controller 230 may offset a
change in the resonance frequency of the source resonator 210 due
to the parasitic capacitor formed between the source resonator 210
and the target device.
FIG. 3 illustrates an example of a wireless power transmitter
300.
A source resonator may form a magnetic coupling with a target
resonator. The source resonator may wirelessly transmit a power to
the target device via the magnetic coupling. As illustrated in FIG.
3, the source resonator includes a first transmission line, a first
conductor 321, a second conductor 322, and at least one first
capacitor 330.
A first capacitor 330 may be inserted in series between a first
signal conducting portion 311 and a second signal conducting
portion 312 in the first transmission line. An electric field may
be confined to be within the first capacitor 330. For example, the
first transmission line may include at least one conductor in an
upper portion of the first transmission line, and the first
transmission line may also include at least one conductor in a
lower portion of the first transmission line. Current may flow
through the at least one conductor disposed in the upper portion of
the first transmission line. The at least one conductor disposed in
the lower portion of the first transmission line may be
electrically grounded. For example, a conductor disposed in an
upper portion of the first transmission line may be separated into
the first signal conducting portion 311 and the second signal
conducting portion 312. A conductor disposed in a lower portion of
the first transmission line may be referred to as a first ground
conducting portion 313.
The source resonator of FIG. 3 may have a two-dimensional (2D)
structure. The first transmission line may include the first signal
conducting portion 311 and the second signal conducting portion
312. The first signal conducting portion 311 and the second signal
conducting portion 312 may be located in the upper portion of the
first transmission line. In addition, the first transmission line
may include the first ground conducting portion 313 in the lower
portion of the first transmission line. The first signal conducting
portion 311 and the second signal conducting portion 312 may face
the first ground conducting portion 313. The current may flow
through the first signal conducting portion 311 and the second
signal conducting portion 312.
As one aspect, one end of the first signal conducting portion 311
may be shorted to the first conductor 321. One end of the second
signal conducting portion 312 may be shorted to the second
conductor 322. The other ends of the first signal conducting
portion 311 and the second signal conducting portion 312 may both
be connected to the first capacitor 330. Accordingly, the first
signal conducting portion 311, the second signal conducting portion
312, the first ground conducting portion 313, and the conductors
321 and 322 may be connected to each other. Thus, the source
resonator may have an electrically closed-loop structure. The term
"loop structure" may have, for example, a polygonal structure such
as a circular structure, a rectangular structure, and the like.
"Having a loop structure" may indicate that the circuit is
electrically closed.
The first capacitor 330 may be inserted into an intermediate
portion of the first transmission line. For example, the first
capacitor 330 may be inserted into a space between the first signal
conducting portion 311 and the second signal conducting portion
312. The first capacitor 330 may have a shape corresponding to a
lumped element, a distributed element, and the like. For example, a
distributed capacitor having the shape of the distributed element
may include zigzagged conductor lines and a dielectric material
having a high permittivity between the zigzagged conductor
lines.
In response to the first capacitor 330 being inserted into the
first transmission line instead of the space between the first
signal conducting portion 311 and the second signal conducting
portion 312, the source resonator may have a characteristic of a
metamaterial. The metamaterial may indicate a material having a
predetermined electrical property that has not been discovered in
nature, and thus, the meta material may have an artificially
designed structure. An electromagnetic characteristic of the
materials existing in nature may have a unique magnetic
permeability or a unique permittivity. Most materials may have a
positive magnetic permeability or a positive permittivity.
In the case of most materials, a right hand rule may be applied to
an electric field, a magnetic field, and a pointing vector, and
thus, the corresponding materials having the right hand rule
applied may be referred to as right handed materials (RHMs). As
another aspect, the metamaterial having a magnetic permeability or
a permittivity absent in nature may be classified into an epsilon
negative (ENG) material, an MNG material, a DNG material, a
negative refractive index (NRI) material, a left-handed (LH)
material, and the like. The classification may be based on a sign
of the corresponding permittivity or magnetic permeability.
In response to a capacitance of the first capacitor 330 inserted as
the lumped element being appropriately determined, the source
resonator may have the characteristic of the metamaterial. The
source resonator may have a negative magnetic permeability based on
an adjustment of the capacitance of the first capacitor 330. Thus,
the source resonator may also be referred to as an MNG resonator.
Various criteria may be used to determine the capacitance of the
first capacitor 330. For example, the various criteria may include
a criterion for enabling the source resonator to have the
characteristic of the metamaterial, a criterion for enabling the
source resonator to have a negative magnetic permeability in a
target frequency, a criterion for enabling the source resonator to
have a zeroth order resonance characteristic in the target
frequency, and the like. Based on any combination of the
aforementioned criteria, the capacitance of the first capacitor 330
may be determined.
The source resonator, also referred to as the MNG resonator, may
have a zeroth order resonance characteristic. The zeroth order
resonance characteristic may have, as a resonance frequency, a
frequency where a propagation constant is "0". Because the source
resonator may have the zeroth order resonance characteristic, the
resonance frequency may be independent of a physical size of the
MNG resonator. The MNG resonator may change the resonance frequency
based on an appropriate design of the first capacitor 330.
Accordingly, the physical size of the MNG resonator may not be
changed.
In a near field, the electric field may be concentrated on the
first capacitor 330 inserted into the first transmission line.
Accordingly, due to the first capacitor 330, the magnetic field may
become dominant in the near field. The MNG resonator may have a
relatively high Q-factor using the first capacitor 330 of the
lumped element, and thus, an enhancement of an efficiency of power
transmission may be possible. For example, the Q-factor may
indicate a level of an ohmic loss or a ratio of a reactance with
respect to a resistance in the wireless power transmission. The
efficiency of the wireless power transmission may increase
corresponding to an increase in the Q-factor.
Although not illustrated in FIG. 3, a magnetic core may be provided
to pass through the MNG resonator. The magnetic core may increase a
power transmission distance.
Referring to FIG. 3, a sub-resonator includes a second transmission
line, a third conductor 351, a fourth conductor 352, and at least
one second capacitor 360.
The second capacitor 360 may be inserted between a third signal
conducting portion 341 and a fourth signal conducting portion 342
in the second transmission line, and an electric field may be
confined to be within the second capacitor 360. As an example, The
second capacitor 360 may be located in series between a third
signal conducting portion 341 and a fourth signal conducting
portion 342.
As illustrated in FIG. 3, the sub-resonator may have a 2D
structure. The second transmission line may include the third
signal conducting portion 341 and the fourth signal conducting
portion 342 in an upper portion of the second transmission line. In
addition, the second transmission line may include a second ground
conducting portion 343 in a lower portion of the second
transmission line. The third signal conducting portion 341 and the
fourth signal conducting portion 342 may face the second ground
conducting portion 343. Current may flow through the third signal
conducting portion 341 and the fourth signal conducting portion
342.
As another aspect, one end of the third signal conducting portion
341 may be shorted to the third conductor 351, and the other end of
the third signal conducting portion 341 may be connected to the
second capacitor 360. One end of the fourth signal conducting
portion 342 may be shorted to the fourth conductor 352, and the
other end of the fourth signal conducting portion 342 may be
connected to the second capacitor 360. Accordingly, the third
signal conducting portion 341, the fourth signal conducting portion
342, the second ground conducting portion 343, the third conductor
351, and the fourth conductor 352 may be connected to each other.
Thus, the sub-resonator may have an electrically closed-loop
structure. The term "loop structure" may refer to, for example, a
polygonal structure such as a circular structure, a rectangular
structure, and the like.
The second transmission line, the third conductor 351, and the
fourth conductor 352 may form, for example, a rectangular loop
structure, a circular loop structure, or a crossed loop
structure.
A magnetic field distribution controller may adjust a resonance
frequency of at least one sub-resonator, based on a value of the
second capacitor 360, and a length and width of the second
transmission line. Thus, the resonance frequency of the
sub-resonator may differ from a resonance frequency of the source
resonator by a predetermined value.
The magnetic field distribution controller may adjust the value of
the second capacitor 360. For example, in response to the value of
the second capacitor 360 being changed, the resonance frequency of
the sub-resonator may also be changed. Accordingly, the magnetic
field distribution controller may adjust the value of the second
capacitor 360 to adjust the resonance frequency of the
sub-resonator to be greater than or less than the resonance
frequency of the source resonator. The magnetic field distribution
controller may adjust the resonance frequency of the sub-resonator
to be greater than or less than the resonance frequency of the
source resonator, so that a magnetic field formed in the center of
the source resonator may have substantially the same strength as a
magnetic field formed outside the source resonator.
FIGS. 4 through 8 illustrate examples of resonators. A source
resonator included in a wireless power transmitter may have a
structure as illustrated in FIGS. 4 through 8.
FIG. 4 illustrates an example of a resonator 400 having a
three-dimensional (3D) structure.
Referring to FIG. 4, the resonator 400 having the 3D structure may
include a transmission line and a capacitor 420. The transmission
line may include a first signal conducting portion 411, a second
signal conducting portion 412, and a ground conducting portion 413.
The capacitor 420 may be located in series between the first signal
conducting portion 411 and the second signal conducting portion 412
of the transmission link. An electric field may be confined within
the capacitor 420.
As illustrated in FIG. 4, the resonator 400 may have the 3D
structure. The transmission line may include the first signal
conducting portion 411 and the second signal conducting portion 412
in an upper portion of the resonator 400, and the resonator 400 may
include a ground conducting portion 413 in a lower portion of the
resonator 400. The first signal conducting portion 411 and the
second signal conducting portion 412 may face the ground conducting
portion 413. For example, current may flow in an x direction
through the first signal conducting portion 411 and the second
signal conducting portion 412. Due to the current, a magnetic field
H(W) may be formed in a -y direction. As another example, unlike
the diagram of FIG. 4, the magnetic field H(W) may be formed in a
+y direction.
One end of the first signal conducting portion 411 may be shorted
to the conductor 442, and the other end of the first signal
conducting portion 411 may be connected to the capacitor 420. One
end of the second signal conducting portion 412 may be grounded to
the conductor 441, and the other end of the second signal
conducting portion 412 may be connected to the capacitor 420.
Accordingly, the first signal conducting portion 411, the second
signal conducting portion 412, the ground conducting portion 413,
and the conductors 441 and 442 may be connected to each other.
Thus, the resonator 400 may have an electrically closed-loop
structure. The term "loop structure" may refer to a polygonal
structure such as, for example, a circular structure, a rectangular
structure, and the like. "Having a loop structure" may indicate
being electrically closed.
As shown in FIG. 4, the capacitor 420 may be inserted between the
first signal conducting portion 411 and the second signal
conducting portion 412. The capacitor 420 may have a shape of a
lumped element, a distributed element, and the like. As an aspect,
a distributed capacitor having the shape of the distributed element
may include zigzagged conductor lines, and the distributed
capacitor may have a dielectric material having a relatively high
permittivity located between the zigzagged conductor lines.
The resonator 400, having the capacitor 420 inserted into the
transmission line, may have a metamaterial property.
In response to a capacitance of the capacitor inserted as the
lumped element being appropriately determined, the resonator 400
may have the characteristic of the metamaterial. Because the
resonator 400 may appropriately adjust the capacitance of the
capacitor 420 to have a negative magnetic permeability, the
resonator 400 may also be referred to as an MNG resonator. Various
criteria may be applied to determine the capacitance of the
capacitor 420. For example, a criterion may enable the resonator
400 to have the characteristic of the metamaterial, a criterion may
enable the resonator 400 to have a negative magnetic permeability
in a target frequency, a criterion may enable the resonator 400 to
have a zeroth order resonance characteristic in the target
frequency, and the like. The capacitance of the capacitor 420 may
be determined based on at least one criterion among the
aforementioned criteria.
The resonator 400, also referred to as the MNG resonator 400, may
have a zeroth order resonance characteristic having, as a resonance
frequency, a frequency where a propagation constant is "0". Because
the resonator 400 may have the zeroth order resonance
characteristic, the resonance frequency may be independent of a
physical size of the MNG resonator 400. The MNG resonator 400 may
appropriately design the capacitor 420 to change the resonance
frequency. Accordingly, the physical size of the MNG resonator 400
may not be changed.
Referring to the MNG resonator 400 of FIG. 4, in a near field, the
electric field may be concentrated on the capacitor 420 inserted
into the transmission line. Accordingly, the magnetic field may
become dominant in the near field due to the capacitor 420. For
example, because the MNG resonator 400 having the zeroth-order
resonance characteristic may have characteristics similar to a
magnetic dipole, the magnetic field may become dominant in the near
field. A relatively small amount of the electric field formed due
to the insertion of the capacitor 420 may be concentrated on the
capacitor 420, and thus, the magnetic field may become further
dominant. The MNG resonator 400 may have a relatively high Q-factor
using the capacitor 420 of the lumped element. Thus, enhancement of
an efficiency of power transmission is possible.
Also, the MNG resonator 400 may include a matcher 430 for impedance
matching. The matcher 430 may appropriately adjust the strength of
magnetic field of the MNG resonator 400. The matcher 430 may
determine an impedance of the MNG resonator 400. Current may flow
into and/or out of the MNG resonator 400 via a connector 440
connected to the ground conducting portion 413 or the matcher
430.
For example, as shown in FIG. 4, the matcher 430 may be positioned
within the loop of the loop structure of the resonator 400. The
matcher 430 may change the physical shape of the matcher 430 to
adjust the impedance of the resonator 400. For example, the matcher
430 may include the conductor 431 for the impedance matching in a
location separate from the ground conducting portion 413 by a
distance h. Adjusting the distance h may change the impedance of
the resonator 400.
Although not illustrated in FIG. 4, a controller may control the
matcher 430. For example, the physical shape of the matcher 430 may
be changed based on a control signal generated by the controller.
For example, the control signal may increase or decrease the
distance h between the conductor 431 of the matcher 430 and the
ground conducting portion 413. Accordingly, the physical shape of
the matcher 430 may be changed to adjust the impedance of the
resonator 400. The distance h between the conductor 431 of the
matcher 430 and the ground conducting portion 413 may be adjusted
using a variety of schemes. As one example, the matcher 430 may
include a plurality of conductors and the distance h may be
adjusted by adaptively activating one of the conductors. As another
example, adjusting the physical location of the conductor 431 up
and down may adjust the distance h. The distance h may be
controlled based on the control signal of the controller. The
controller may generate the control signal using various
factors.
As shown in FIG. 4, the matcher 430 may be configured as a passive
element such as the conductor 431. Depending on examples, the
matcher 430 may be configured as an active element. The active
element may be a diode, a transistor, and the like. In response to
the active element being included in the matcher 430, the active
element may be driven based on the control signal generated by the
controller, and the impedance of the resonator 400 may be adjusted
based on the control signal. For example, a diode may be included
in the matcher 430 where the diode is a type of active element. For
example, the impedance of the resonator 400 may be adjusted based
on whether the state of the diode where the diode is in an ON state
or an OFF state.
Although not illustrated in FIG. 4, a magnetic core may be provided
to pass through the resonator 400 configured as the MNG resonator.
The magnetic core may increase a power transmission distance.
FIG. 5 illustrates an example of a bulky-type resonator 500 for
wireless power transmission.
Referring to FIG. 5, a first signal conducting portion 511 and a
second signal conducting portion 512 may be integrally formed
instead of being separately manufactured and thereafter connected
to each other. As another example, the second signal conducting
portion 512 and the conductor 541 may be integrally
manufactured.
In response to the second signal conducting portion 512 and the
conductor 541 being separately manufactured and then connected to
each other, a loss of conduction may occur at seam 550. The second
signal conducting portion 512 and the conductor 541 may be
connected to each other without using a separate seam. In other
words, the second signal conducting portion 512 and the conductor
541 may be seamlessly connected to each other. Accordingly, a
conductor loss caused by the seam 550 may be decreased. As another
example, the second signal conducting portion 512 and a ground
conducting portion 513 may be seamlessly and integrally
manufactured. As yet another example, the first signal conducting
portion 511 and the ground conducting portion 513 may be seamlessly
and integrally manufactured.
Referring to FIG. 5, a type of a seamless connection connecting at
least two partitions into an integrated form may be referred to as
a bulky type.
FIG. 6 illustrates an example of a hollow-type resonator 600 for
wireless power transmission.
Referring to FIG. 6, each of a first signal conducting portion 611,
a second signal conducting portion 612, a ground conducting portion
613, and conductors 641 and 642 of the hollow type resonator 600
include an empty or hollow space inside.
For a given resonance frequency, an active current may be modeled
to flow in only a portion of the first signal conducting portion
611 instead of the entire first signal conducting portion 611, the
active current may be modeled to flow in only a portion of the
second signal conducting portion 612 instead of the entire second
signal conducting portion 612, the active current may be modeled to
flow in only a portion of the ground conducting portion 613 instead
of the entire ground conducting portion 613, active current may be
modeled to flow in only a portion of the conductors 641 and 642
instead of the entire conductors 641 and 642, or in any combination
thereof. For example, in response to a depth of each of the first
signal conducting portion 611, the second signal conducting portion
612, the ground conducting portion 613, and the conductors 641 and
642 being significantly deeper than a corresponding skin depth in
the given resonance frequency, the hollow type resonator 600 may be
ineffective. As a result, the significantly deeper depth may
increase a weight or manufacturing costs of the resonator 600.
Accordingly, for the given resonance frequency, the depth of each
of the first signal conducting portion 611, the second signal
conducting portion 612, the ground conducting portion 613, and the
conductors 641 and 642 may be determined based on the corresponding
skin depth of each of the first signal conducting portion 611, the
second signal conducting portion 612, the ground conducting portion
613, and the conductors 641 and 642. In response to each of the
first signal conducting portion 611, the second signal conducting
portion 612, the ground conducting portion 613, and the conductors
641 and 642 having an appropriate depth deeper than a corresponding
skin depth, the resonator 600 may become lighter in weight, and
manufacturing costs of the resonator 600 may also decrease.
For example, as shown in FIG. 6, the depth of the second signal
conducting portion 612 may correspond with "d" mm and d may be
calculated according to
.pi..times..times..times..times..mu..times..times..sigma.
##EQU00001## In this example, f corresponds with a frequency, .mu.
corresponds with a magnetic permeability, and .sigma. corresponds
with a conductor constant. For example, in response to the first
signal conducting portion 611, the second signal conducting portion
612, the ground conducting portion 613, and the conductors 641 and
642 being made of copper and having a conductivity of
5.8.times.10.sup.7 siemens per meter (Sm.sup.-1), the skin depth
may be about 0.6 mm with respect to 6 kHz of the resonance
frequency and the skin depth may be about 0.006 mm with respect to
60 MHz of the resonance frequency.
FIG. 7 illustrates a resonator 700 for wireless power transmission
using a parallel-sheet.
Referring to FIG. 7, the parallel-sheet may be applied to each of a
first signal conducting portion 711 and a second signal conducting
portion 712 included in the resonator 700.
Each of the first signal conducting portion 711 and the second
signal conducting portion 712 may have a resistance. Thus, first
signal conducting portion 711 and the second signal conducting
portion 712 may not be a perfect conductor. Due to the resistance,
an ohmic loss may occur, which may decrease a Q-factor and also a
coupling effect.
By applying the parallel-sheet to each of the first signal
conducting portion 711 and the second signal conducting portion
712, a decrease in the ohmic loss, and an increase in the Q-factor
and the coupling effect may be possible. Referring to a portion 770
indicated by a circle, in response to the parallel-sheet being
applied, each of the first signal conducting portion 711 and the
second signal conducting portion 712 may include a plurality of
conductor lines. For example, the plurality of conductor lines may
be disposed in parallel, and may be shorted at an end portion of
each of the first signal conducting portion 711 and the second
signal conducting portion 712.
As described above, in response to the parallel-sheet being applied
to each of the first signal conducting portion 711 and the second
signal conducting portion 712, the plurality of conductor lines may
be disposed in parallel. Accordingly, a sum of resistances having
the conductor lines may be decreased. Accordingly, the resistance
loss may decrease, and the Q-factor and the coupling effect may
increase.
FIG. 8 illustrates an example of a resonator 800 for wireless power
transmission that includes a distributed capacitor.
Referring to FIG. 8, a capacitor 820 may be included in the
resonator 800 for the wireless power transmission. The capacitor
820 may be a distributed capacitor. A capacitor as a lumped element
may have a relatively high equivalent series resistance (ESR). A
variety of schemes have been proposed to decrease the ESR contained
in the capacitor of the lumped element. According to an example, by
using the capacitor 820 as a distributed element, a decrease in the
ESR is possible. A loss caused by the ESR may decrease a Q-factor
and a coupling effect.
As shown in FIG. 8, the capacitor 820 may have a zigzagged
structure. The capacitor 820 may be the distributed element. For
example, the capacitor 820 as the distributed element may be
configured as a conductive line and a conductor having the
zigzagged structure.
As shown in FIG. 8, employing the capacitor 820 as the distributed
element may cause a decrease in the loss occurring due to the ESR.
In addition, by disposing a plurality of capacitors as lumped
elements, a decrease in the loss occurring due to the ESR may be
possible. Because a resistance of each of the capacitors as the
lumped elements decreases through a parallel connection, active
resistances of parallel-connected capacitors as the lumped elements
may also decrease. Thus, the loss occurring due to the ESR may
decrease. For example, employing ten capacitors of 1 pF instead of
using a single capacitor of 10 pF, may decrease the loss occurring
due to the ESR.
FIG. 9 illustrates an example of an equivalent circuit of the
resonator for wireless power transmission of FIG. 3.
The resonator of FIG. 3 may be modeled to the equivalent circuit of
FIG. 9. In the equivalent circuit of FIG. 9, C.sub.L may correspond
to a capacitor that is inserted in the form of a lumped element at
approximately the middle of one of the transmission lines of FIG.
3.
In this example, the resonator of FIG. 3 may have a zeroth
resonance characteristic. For example, in response to a propagation
constant being "0", the resonator of FIG. 3 may have
.omega..sub.MZR as a resonance frequency. The resonance frequency
.omega..sub.MZR may be expressed by Equation 1.
.omega..times..times..times. ##EQU00002##
In Equation 1, MZR correspond to a M.mu. zero resonator.
Referring to Equation 1, the resonance frequency .omega..sub.MZR of
the resonator of FIG. 3 may be determined by L.sub.R/C.sub.L. A
physical size of the resonator of FIG. 3 and the resonance
frequency .omega..sub.MZR may be independent of each other. Because
the physical sizes are independent with respect to each other, the
physical size of the resonator of FIG. 3 may be sufficiently
reduced.
FIG. 10 illustrates an example of a configuration of a wireless
power receiving and transmitting system 1000.
The wireless power receiving and transmitting system 1000 may
include a transmission apparatus, and a reception apparatus.
The transmission apparatus may include a signal generator 1010, a
power amplifier 1020, and a source resonator 1030. An example of
the transmission apparatus may be a wireless power transmitter.
The reception apparatus may include a target resonator 1040, a
rectifier 1050, and a DC/DC converter 1060. An example of the
reception apparatus may be a wireless power receiver.
The transmission apparatus may refer to a system that wirelessly
provides a power to the reception apparatus. The signal generator
1010 may generate a signal used to transmit wireless power. The
generated signal may be sent to the power amplifier 1020.
The power amplifier 1020 may amplify the generated signal to be
suitable for transmission through the source resonator 1030. The
power amplifier 1020 may amplify the signal, and the signal may be
provided to the source resonator 1030.
The source resonator 1030 may wirelessly transmit the amplified
signal to the reception apparatus through resonance.
In other words, power may be transmitted through resonance between
the source resonator 1030 of the transmission apparatus, and the
target resonator 1040 of the reception apparatus.
The reception apparatus may refer to a system that wirelessly
receives a power from the transmission apparatus, and the reception
apparatus may use the received power.
The reception apparatus may be implemented for a low power
application using a 10 power equal to or less than 10 W.
The target resonator 1040 may receive a wirelessly transmitted
signal from the source resonator 1030. In other words, the target
resonator 1040 may receive a power wirelessly.
The target resonator 1040 may be provide the received signal to the
rectifier 1050.
The rectifier 1050 may rectify the received signal. In other words,
the received signal may be the received power.
The DC/DC converter 1060 may convert the rectified signal. As an
example, the DC/DC converter 1060 may convert the power rectified
by the rectifier 1050. The converted power may have, for example, a
voltage suitable to be provided to a load connected to the
receiver.
The DC/DC converter 1060 may be implemented, for example, as a buck
converter. In other words, the buck converter may be a switching
regulator.
For commercialization of wireless power transmission, the total
efficiency of the wireless power receiving and transmitting system
1000 may be at least 60%, as illustrated in Table 1 below. The
total efficiency may be obtained by summing up an efficiency of the
signal generator 1010, an efficiency of the power amplifier 1020,
an efficiency of power transfer from the source resonator 1030 to
the target resonator 1040 (namely, an efficiency of power transfer
from a resonator to a resonator), an efficiency of the rectifier
1050, and an efficiency of the DC/DC converter 1060.
TABLE-US-00001 TABLE 1 Efficiency of the signal Efficiency of
generator 1010 + power transfer Efficiency of the Efficiency from
the source rectifier 1050 + of the power resonator 1030 to the
Efficiency of the amplifier 1020 target resonator 1040 DC/DC
converter 1060 Total 85% 90% 80% >60%
To achieve the total efficiency, the sum of the efficiency of the
signal generator 1010 and the efficiency of the power amplifier
1020, the efficiency of power transfer from the source resonator
1030 to the target resonator 1040, and the sum of the efficiency of
the rectifier 1050 and the efficiency of the DC/DC converter 1060
may be respectively at least 85%, 90%, and 80%.
Typically, for commercialization of wireless power transmission,
the DC/DC converter 1060 may have an efficiency of about 92%.
Accordingly, to enable the sum of the efficiency of the rectifier
1050 and the efficiency of the DC/DC converter 1060 to reach at
least 80%, the efficiency of the rectifier 1050 may be at least
90%.
To obtain a rectification operation having an efficiency of at
least 90% in an RF band greater than 1 MHz, a Schottky diode may be
used as a basic diode of the rectifier 1050.
The Schottky diode may have a low voltage drop. Additionally, a
majority carrier may carry an electric charge of the Schottky
diode. In other words, since the majority carrier may not
accumulate the electric charge, the Schottky diode may have a high
speed.
The Schottky diode having the low voltage drop may be used to
configure a rectifier circuit of a wireless power transmission
employing a resonance scheme using an RF band of 1 MHz to 15
MHz.
FIG. 11 illustrates an example of an equivalent model of a Schottky
diode.
A Schottky diode 1110 may include an ideal diode 1120, a voltage
V.sub.on 1130, and a resistance R.sub.on 1140. The voltage V.sub.on
1130 may be used in response to the Schottky diode 1110 being
turned on, and a characteristic of the resistance R.sub.on 1140 may
be changed depending on a flowing current.
In the Schottky diode 1110, the ideal diode 1120, the voltage
V.sub.on 1130, and the resistance R.sub.on 1140 may be connected in
series.
Schottky diodes may have various performances based on
manufacturers or manufacturing processes. Accordingly, to design a
rectifier current with a high efficiency, selecting a Schottky
diode having a voltage drop that is equal to or less than a
predetermined value at a predetermined current level may be
desired.
FIGS. 12A and 12B illustrate examples of a current-to-voltage
characteristic of a Schottky diode.
In FIGS. 12A and 12B, V.sub.F [V] may correspond with a forward
voltage in volts (V).
Additionally, I.sub.F [A] may correspond with a forward current in
amperes (A).
T.sub.A may relate to a temperature, for example, a room
temperature.
A first graph 1210 of FIG. 12A may may relate to a first Schottky
diode. A second graph 1220 of FIG. 12B may may relate to a second
Schottky diode. The first Schottky diode and the second Schottky
diode may be produced by different manufacturers or produced by
different processes.
The first Schottky diode, and the second Schottky diode may be used
in wireless power transmission to a mobile.
As illustrated in the first graph 1210 and the second graph 1220, a
voltage drop may increase corresponding to an increase in
current.
As an example, a current of 0.5 A may flow in the first Schottky
diode, correspondingly, a voltage drop of the first Schottky diode
may relate to 0.48 V, as illustrated in the first graph 1210.
In another example, a current of 0.5 A may flow in the second
Schottky diode, correspondingly, a voltage drop of the second
Schottky diode may relate to 0.3 V, as illustrated in the second
graph 1220.
FIG. 13 illustrates an example of a full-bridge diode rectifier
circuit.
In the full-bridge diode rectifier circuit, a single path may pass
through two diodes. In other words, a current may pass through the
two diodes in the single path.
In an example, a rectifier may be configured to use the first
Schottky diode of FIG. 12A, in response to a current of 0.5 A
flowing in the rectifier, a voltage drop may correspond to 0.96 V
(2.times.0.48=0.96V). Accordingly, the first Schottky diode (0.96
V.times.0.5 A=0.48 W) may consume a power of 0.48 W.
Assuming that a power of 2.5 W is consumed in a load, in response
to a reception apparatus having an efficiency of 80%, an RF power
of 3.125 W may be input (2.5/0.8=3.125 W).
In this example, an efficiency .eta..sub.(a)rectifier of a
full-bridge diode rectifier may be obtained using the following
Equation 2:
.thrfore..eta..times..times..times..times..times. ##EQU00003##
In Equation 2, P.sub.RF corresponds to an input RF power, and
P.sub.2.times.Drop corresponds to a power consumed in a diode.
In another example, a rectifier may use the second Schottky diode
of FIG. 12B. In response to a current of 0.5 A flowing in the
rectifier, a voltage drop may correspond to 0.6 V
(2.times.0.3=0.6V). Accordingly, the second Schottky diode (0.6
V.times.0.5 A=0.3 W) may consume a power of 0.3 W.
Assuming that a power of 2.5 W is consumed in a load, in response
to a reception apparatus having an efficiency of 80%, an RF power
of 3.125 W may be input (2.5/0.8=3.125 W).
In this example, an efficiency .eta..sub.(b)rectifier of a
full-bridge diode rectifier may be determined using the following
Equation 3:
.thrfore..eta..times..times..times..times..times. ##EQU00004##
To enable the efficiency of the rectifier 1050 to reach at least
90%, a Schottky diode in which a voltage drop is equal to or less
than 0.3V in response to a current of 0.5 A flowing may be desired
to be used. As another aspect, few Schottky diodes may have a small
size and low cost while having a voltage drop that is equal to or
less than 0.3V in response to a current of 0.5 A flowing.
Thus, a rectifier circuit having a voltage drop performance
improved using a dual diode may be used. The rectifier circuit may
include a Schottky diode rectifier.
FIG. 14 illustrates an example of a structure of a dual diode
full-bridge rectifier 1400.
The dual diode full-bridge rectifier 1400 may be, for example, the
rectifier 1050 of FIG. 10.
The rectifier 1050, for example the dual diode full-bridge
rectifier 1400, may receive the power from the target resonator
1040 via a positive RF port (RF+) and a negative RF port (RF-).
The target resonator 1040 may output differential signals referred
to as RF+ and RF-. In other words, RF+ and RF- may indicate
differential input signals. RF+ may be a positive-phase signal, and
RF- may be a negative-phase signal.
The rectifier 1050 may rectify a signal referred to as a positive
DC port (DC+), and the positive DC port (DC+) may be output from
the rectifier 1050.
The dual diode full-bridge rectifier 1400 may include a first
rectification unit 1410, a second rectification unit 1420, a third
rectification unit 1430, a fourth rectification unit 1440, and a
capacitor 1450.
An anode 1412 and a cathode 1414 of the first rectification unit
1410 may be connected to RF- and DC+, respectively.
An anode 1422 and a cathode 1424 of the second rectification unit
1420 may be connected to RF+ and DC+, respectively.
An anode 1432 and a cathode 1434 of the third rectification unit
1430 may be connected to a ground and RF-, respectively.
An anode 1442 and a cathode 1444 of the fourth rectification unit
1440 may be connected to the ground and RF+, respectively.
The capacitor 1450 may be connected to DC+ and the ground. As an
aspect, one end of the capacitor 1450 may be connected to DC+, and
another end of the capacitor 1450 may be connected to the
ground.
Each of the first rectification unit 1410, the second rectification
unit 1420, the third rectification unit 1430, and the fourth
rectification unit 1440 may include two Schottky diodes. The two
Schottky diodes may be connected in parallel. For example, an anode
of each of two Schottky diodes may be connected to an anode of a
rectification unit, and a cathode of each of the two Schottky
diodes may be connected to a cathode of the rectification unit.
In a dual diode mode, diodes, for example two Schottky diodes, may
be used in parallel, and the diodes may enable current to pass
through two paths, thereby reducing a voltage drop.
As illustrated in FIG. 14, the first rectification unit 1410 may
include, for example, two Schottky diodes 1416 and 1418. In other
words, a number of Schottky diodes in each rectification unit may
be two.
Additionally, the first rectification unit 1410, the second
rectification unit 1420, the third rectification unit 1430, and the
fourth rectification unit 1440 each may include a plurality of
Schottky diodes that are connected in parallel.
FIGS. 15A and 15B illustrate examples of a current-to-voltage curve
indicating a voltage drop of the dual diode full-bridge rectifier
1400 of FIG. 14.
As illustrated in a first graph 1510 of FIG. 15A, in response to a
current of 0.5 A flowing in a first Schottky diode, a voltage drop
of the first Schottky diode may correspond to 0.48 V. For example,
in response to two first Schottky diodes being used in parallel, a
current of 0.25 A may flow in each of the two first Schottky
diodes. In this example, a voltage drop of a dual diode may
correspond to 0.4 V.
In the dual diode full-bridge rectifier 1400, a single path may
pass through two diodes in series. Accordingly, a total voltage
drop may correspond to 0.8 V (2.times.0.4=0.8 V).
Thus, a power of 0.4 W may be consumed in the two first Schottky
diodes (0.8 V.times.0.5 A=0.4 W).
As an example, a power of 2.5 W may be consumed in a load. In
response to a reception apparatus having an efficiency of 80%, an
RF power of 3.125 W may be input (2.5/0.8=3.125 W).
Accordingly, an efficiency .eta..sub.(a)rectifier2 of the dual
diode full-bridge rectifier 1400 may occur based on the following
Equation 4:
.thrfore..eta..times..times..times..times..times..times..times.
##EQU00005##
Additionally, as illustrated in a second graph 1520 of FIG. 15B, in
response to a current of 0.5 A flowing in a second Schottky diode,
a voltage drop of the second Schottky diode may correspond to 0.3
V. For example, in response to two second Schottky diodes being
used in parallel, a current of 0.25 A may flow in each of the two
second Schottky diodes. In this example, a voltage drop of a dual
diode may correspond to 0.26 V.
In the dual diode full-bridge rectifier 1400, a single path may
pass through two diodes in series. Accordingly, a total voltage
drop may correspond to 0.52 V (2.times.0.26=0.52 V).
Accordingly, a power of 0.26 W may be consumed in the two second
Schottky diodes (0.52 V.times.0.5 A=0.26 W).
A power of 2.5 W may be consumed in a load. In response to a
reception apparatus having an efficiency of 80%, an RF power of
3.125 W may be input (2.5/0.8=3.125 W).
Accordingly, an efficiency .eta..sub.(b)rectifier2 of the dual
diode full-bridge rectifier 1400 may be obtained using the
following Equation 5:
.thrfore..eta..times..times..times..times..times..times..times.
##EQU00006##
Thus, the efficiency of the rectifier 1050 may be increased by 2%
to 3%, using the dual diode.
Additionally, since Schottky diodes are used in parallel, an amount
of current flowing in each of the diodes may be reduced to half.
Accordingly, using diodes that are connected in parallel may double
an allowable current amount of a diode, and using diodes that are
connected in parallel may also contribute to ensuring a stability
and reliability of an operation of a rectifier.
Thus, an improvement in efficiency of a rectifier itself by using a
dual diode in wireless power transmission, without replacement of a
diode, and an improvement in overall system efficiency are
possible.
FIGS. 16A and 16B illustrate examples of a current-to-voltage curve
indicating a voltage drop of a full-bridge rectifier in which three
Schottky diodes are used in parallel.
As an example, FIGS. 16A and 16B illustrate a voltage drop in which
a rectification unit is formed with three diodes, instead of two
diodes of the dual diode full-bridge rectifier 1400 of FIG. 14.
As illustrated in a first graph 1610 of FIG. 16A, in response to a
current of 0.5 A flowing in a first Schottky diode, a voltage drop
of the first Schottky diode corresponds to 0.48V. For example, in
response to three first Schottky diodes being used in parallel, a
current of 0.17 A may flow in each of the three first Schottky
diodes. In this example, a voltage drop may correspond to 0.38
V.
An efficiency .eta..sub.(a)rectifier3 of a rectifier may be
obtained using the following Equation 6:
.thrfore..eta..times..times..times..times..times..times..times.
##EQU00007##
As illustrated in a second graph 1620 of FIG. 16B, in response to a
current of 0.5 A flowing in a second Schottky diode, a voltage drop
of the second Schottky diode corresponds to 0.3V. For example, in
response to three second Schottky diodes being used in parallel, a
current of 0.17 A may flow in each of the three second Schottky
diodes. In this example, a voltage drop may correspond to 0.25
V.
An efficiency .eta..sub.(b)rectifier3 of a rectifier may be
obtained using the following Equation 7:
.thrfore..eta..times..times..times..times..times..times..times.
##EQU00008##
In other words, in response to three diodes being used in parallel
in a rectifier, an efficiency of the rectifier may be increased by
0.4% to 0.6%, compared to a rectifier employing a dual diode.
FIG. 17 illustrates an example of a structure of a dual diode
cross-coupled transistor (TR) rectifier 1700.
The dual diode cross-coupled TR rectifier 1700 may be, for example,
the rectifier 1050 of FIG. 10.
To reduce an influence of a voltage drop of a diode, the dual diode
cross-coupled TR rectifier 1700 may be configured using
N-metal-oxide-semiconductor field-effect transistors (N-MOSFETs),
instead of diodes of the third rectification unit 1430 and the
fourth rectification unit 1440 in the dual diode full-bridge
rectifier 1400 of FIG. 14.
The dual diode cross-coupled TR rectifier 1700 may include a first
rectification unit 1710, a second rectification unit 1720, a third
rectification unit 1730, a fourth rectification unit 1740, and a
capacitor 1750.
An anode 1712 and a cathode 1714 of the first rectification unit
1710 may be connected to RF- and DC+, respectively.
An anode 1722 and a cathode 1724 of the second rectification unit
1720 may be connected to RF+ and DC+, respectively.
The capacitor 1750 may be connected to DC+ and a ground. For
example, one end of the capacitor 1750 may be connected to DC+, and
another end of the capacitor 1750 may be connected to the
ground.
Each of the first rectification unit 1710 and the second
rectification unit 1720 may include two Schottky diodes. The two
Schottky diodes may be connected in parallel. For example, an anode
of each of two Schottky diodes may be connected to an anode of a
rectification unit, and a cathode each of the two Schottky diodes
may be connected to a cathode of the rectification unit.
The first rectification unit 1710 may include, for example, two
Schottky diodes 1716 and 1718.
Additionally, the first rectification unit 1710 and the second
rectification unit 1720 may each include a plurality of Schottky
diodes that are connected in parallel.
The third rectification unit 1730 may include a first N-MOSFET
1732, and the fourth rectification unit 1740 may include a second
N-MOSFET 1742.
A gate 1734 and a source 1736 of the first N-MOSFET 1732 may be
connected to RF+ and RF-, respectively. Additionally, a drain 1738
of the first N-MOSFET 1732 may be connected to the ground.
A gate 1744 of the second N-MOSFET 1742 may be connected to RF-,
and a source 1746 of the second N-MOSFET 1742 may be connected to
the ground. Additionally, a drain is 1748 of the second N-MOSFET
1742 may be connected to RF+.
Although various types of N-MOSFET may exist, an N-MOSFET device
having a low resistance and a low input capacitance may be
selected, to use the N-MOSFET device in a wireless power
transmission rectifier circuit employing a resonance scheme in a
band of 1 MHz to 15 MHz.
For example, in response to an N-MOSFET device having a resistance
R.sub.on equal to or less than 200 milliohm (m.OMEGA.) and an input
capacitance equal to or less than 300 picofarads (pF) in a band of
1 MHz is used, designing a rectifier with a similar efficiency to
an efficiency of a full-bridge rectifier employing a Schottky diode
in an operating frequency of about 6 MHz may be possible.
Hereinafter, description will be given of an efficiency of the dual
diode cross-coupled TR rectifier 1700 in which a current of 0.5 A
flows, the first Schottky diode of FIG. 12A is used, and an
N-MOSFET having a resistance R.sub.on of 200 m.OMEGA. and an input
capacitance of 300 pF (1 MHz) is used.
A power P.sub.diode of 0.13 W may be consumed in a single dual
diode (2.26 V.times.0.5 A=0.13 W). A power P.sub.Ron of 0.0375 W
may be consumed in the resistance R.sub.on. Adding a parasitic loss
(+.alpha.) P.sub.parastic to 0.0375 W ((0.5
A).sup.2.times.0.2552=0.0375 W) may obtain a power consumed in the
N-MOSFET.
The parasitic loss (+.alpha.) P.sub.parastic may be determined by
the input capacitance, and the parasitic loss (+.alpha.)
P.sub.parastic may be reduced as a frequency decreases.
Additionally, in a band of 6 MHz, the parasitic loss (+.alpha.)
P.sub.parastic may correspond to about 0.1 W.
Accordingly, an efficiency .eta..sub.(CTR)rectifier of the dual
diode cross-coupled TR rectifier 1700 may be obtained using the
following Equation 8:
.thrfore..eta..times..times..times..times..times. ##EQU00009##
Thus, the efficiency of the wireless power receiving and
transmitting system 1000 may reach 90% or higher, by using the dual
diode full-bridge rectifier 1400 or the dual diode cross-coupled TR
rectifier 1700.
FIG. 18 illustrates a result of comparing the efficiency of the
dual diode full-bridge rectifier 1400 of FIG. 14 with the
efficiency of the dual diode cross-coupled TR rectifier 1700 of
FIG. 17.
The efficiency of the dual diode full-bridge rectifier 1400 of FIG.
14, and the efficiency of the dual diode cross-coupled TR rectifier
1700 of FIG. 17 may be compared based on a frequency and an input
capacitance of an N-MOSFET.
As illustrated in FIG. 18, the efficiency of the dual diode
full-bridge rectifier 1400 may remain unchanged despite a change in
frequency, whereas the efficiency of the dual diode cross-coupled
TR rectifier 1700 may change based on a change in input capacitance
and frequency.
Accordingly, to design a rectifier with a high efficiency, an
appropriate rectifier structure may be selected based on an
operating frequency.
FIG. 19 illustrates an example of a power receiving method.
In 1910, the target resonator 1040 of FIG. 10 may receive a
power.
In 1920, the rectifier 1050 of FIG. 10 may receive the power from
the target resonator 1040 via RF+ and RF-, and rectify the received
power.
The rectifier 1050 may be, for example, the dual diode full-bridge
rectifier 1400 of FIG. 14 or the dual diode cross-coupled TR
rectifier 1700 of FIG. 17.
In 1930, the DC/DC converter 1060 of FIG. 10 may convert the
rectified power.
Technical information described above with reference to FIGS. 1 to
18 may be applied to the example of FIG. 19 and accordingly,
further descriptions thereof will be omitted for conciseness.
Program instructions to perform a method described herein, or one
or more operations thereof, may be recorded, stored, or fixed in
one or more computer-readable storage media. The program
instructions may be implemented by a computer. For example, the
computer may cause a processor to execute the program instructions.
The media may include, alone or in combination with the program
instructions, data files, data structures, and the like. Examples
of computer-readable media include magnetic media, such as hard
disks, floppy disks, and magnetic tape; optical media such as CD
ROM disks and DVDs; magneto-optical media, such as optical disks;
and hardware devices that are specially configured to store and
perform program instructions, such as read-only memory (ROM),
random access memory (RAM), flash memory, and the like. Examples of
program instructions include machine code, such as produced by a
compiler, and files containing higher level code that may be
executed by the computer using an interpreter. The program
instructions, that is, software, may be distributed over network
coupled computer systems so that the software is stored and
executed in a distributed fashion. For example, the software and
data may be stored by one or more computer readable recording
mediums. Also, functional programs, codes, and code segments for
accomplishing the example embodiments disclosed herein can be
easily construed by programmers skilled in the art to which the
embodiments pertain based on and using the flow diagrams and block
diagrams of the figures and their corresponding descriptions as
provided herein. Also, the described unit to perform an operation
or a method may be hardware, software, or some combination of
hardware and software. For example, the unit may be a software
package running on a computer or the computer on which that
software is running. A number of examples have been described
above. Nevertheless, it will be understood that various
modifications may be made. For example, suitable results may be
achieved if the described techniques are performed in a different
order and/or if components in a described system, architecture,
device, or circuit are combined in a different manner and/or
replaced or supplemented by other components or their equivalents.
Accordingly, other implementations are within the scope of the
following claims.
* * * * *